U.S. patent application number 16/896304 was filed with the patent office on 2020-12-24 for plasma processing method and plasma processing apparatus.
This patent application is currently assigned to Tokyo Electron Limited. The applicant listed for this patent is Tokyo Electron Limited. Invention is credited to Jun ABE, Yusuke AOKI, Kazunobu FUJIWARA, Shinya MORIKITA, Koichi NAGAMI, Fumiya TAKATA, Toshikatsu TOBANA.
Application Number | 20200402805 16/896304 |
Document ID | / |
Family ID | 1000004903275 |
Filed Date | 2020-12-24 |
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United States Patent
Application |
20200402805 |
Kind Code |
A1 |
AOKI; Yusuke ; et
al. |
December 24, 2020 |
PLASMA PROCESSING METHOD AND PLASMA PROCESSING APPARATUS
Abstract
A plasma processing method according to an exemplary embodiment
includes generating plasma from a film formation gas in a chamber
of a plasma processing apparatus by supplying radio frequency power
from a radio frequency power source. The plasma processing method
further includes forming a protective film on an inner wall surface
of a side wall of the chamber by depositing a chemical species from
the plasma on the inner wall surface. In the forming a protective
film, a pulsed negative direct-current voltage is periodically
applied from a direct-current power source device to an upper
electrode of the plasma processing apparatus.
Inventors: |
AOKI; Yusuke; (Kurokawa-gun,
JP) ; TOBANA; Toshikatsu; (Kurokawa-gun, JP) ;
TAKATA; Fumiya; (Kurokawa-gun, JP) ; MORIKITA;
Shinya; (Kurokawa-gun, JP) ; FUJIWARA; Kazunobu;
(Kurokawa-gun, JP) ; ABE; Jun; (Kurokawa-gun,
JP) ; NAGAMI; Koichi; (Kurokawa-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Tokyo |
|
JP |
|
|
Assignee: |
Tokyo Electron Limited
Tokyo
JP
|
Family ID: |
1000004903275 |
Appl. No.: |
16/896304 |
Filed: |
June 9, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 2237/335 20130101;
C23C 16/4405 20130101; H01J 37/3244 20130101; H01L 21/02115
20130101; H01L 21/3065 20130101; H05H 1/24 20130101; H01J 37/32082
20130101; H01L 21/02123 20130101; H01J 37/32477 20130101 |
International
Class: |
H01L 21/3065 20060101
H01L021/3065; H01J 37/32 20060101 H01J037/32; H01L 21/02 20060101
H01L021/02; H05H 1/24 20060101 H05H001/24; C23C 16/44 20060101
C23C016/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2019 |
JP |
2019-112618 |
Claims
1. A plasma processing method performed using a plasma processing
apparatus, wherein the plasma processing apparatus includes: a
chamber including a side wall having an inner wall surface; a
substrate support including a lower electrode provided in the
chamber; an upper electrode provided above the substrate support; a
radio frequency power source for generating plasma in the chamber;
and a direct-current power source device electrically connected to
the upper electrode, the direct-current power source device being
configured to periodically generate a pulsed negative
direct-current voltage, the plasma processing method comprising:
generating plasma from a film formation gas in the chamber by
supplying radio frequency power from the radio frequency power
source; and forming a protective film on the inner wall surface by
depositing a chemical species from the plasma on the inner wall
surface, wherein the pulsed negative direct-current voltage is
periodically applied from the direct-current power source device to
the upper electrode in said forming a protective film.
2. The plasma processing method according to claim 1, wherein the
film formation gas includes a silicon-containing gas.
3. The plasma processing method according to claim 2, wherein the
silicon-containing gas is a silicon halide gas.
4. The plasma processing method according to claim 3, wherein the
silicon halide gas is a silicon tetrachloride gas.
5. The plasma processing method according to claim 1, wherein the
film formation gas includes a carbon-containing gas.
6. The plasma processing method according to claim 5, wherein the
carbon-containing gas is a hydrocarbon gas or a fluorocarbon
gas.
7. The plasma processing method according to claim 1, wherein an
output voltage of the direct-current power source device is the
pulsed negative direct-current voltage in a first period within a
cycle, and is zero volts in a second period remaining within the
cycle.
8. The plasma processing method according to claim 7, wherein an
effective value of the output voltage of the direct-current power
source device in said forming a protective film is smaller than 0 V
and equal to or larger than -848 V, and the effective value is a
product of a square root of a duty ratio and a value of the pulsed
negative direct-current voltage in the first period, the duty ratio
being a ratio of a time length of the first period to a time length
of the cycle,.
9. The plasma processing method according to claim 8, further
comprising performing plasma processing on a substrate in the
chamber after said forming a protective film, wherein in said
performing plasma processing, plasma is generated from a processing
gas in the chamber by supplying radio frequency power from the
radio frequency power source, the effective value of the output
voltage of the direct-current power source device is set to a value
smaller than the effective value in said forming a protective film,
and the substrate is processed by a chemical species from the
plasma generated from the processing gas.
10. The plasma processing method according to claim 8 further
comprising removing the protective film, wherein in said removing
the protective film, plasma is generated from a cleaning gas in the
chamber by supplying radio frequency power from the radio frequency
power source, the effective value of the output voltage of the
direct-current power source device is set to a value larger than
the effective value in the said forming a protective film, and the
protective film is processed by a chemical species from the plasma
generated from the cleaning gas.
11. A plasma processing apparatus comprising: a chamber including a
side wall having an inner wall surface; a substrate support
including a lower electrode provided in the chamber; an upper
electrode provided above the substrate support; a radio frequency
power source for generating plasma in the chamber; a direct-current
power source device electrically connected to the upper electrode;
and a controller configured to control the radio frequency power
source and the direct-current power source device, wherein the
direct-current power source device is configured to periodically
generate a pulsed negative direct-current voltage, and the
controller is configured to control the radio frequency power
source to supply radio frequency power to generate plasma from a
film formation gas in the chamber, and control the direct-current
power source device to periodically apply the pulsed negative
direct-current voltage to the upper electrode to form a protective
film on the inner wall surface by depositing a chemical species
from the plasma on the inner wall surface.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims the benefit of
priority from Japanese Patent Application No. 2019-112618 filed on
Jun. 18, 2019, the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Exemplary embodiments of the present disclosure relate to a
plasma processing method and a plasma processing apparatus.
BACKGROUND
[0003] A plasma processing apparatus is used for plasma processing
on a substrate. A protective film is formed on the inner wall
surface of a chamber of a plasma processing apparatus before
performing plasma processing on a substrate in some cases. Japanese
Patent Application Laid-Open Publication No. 2014-138027 and
Japanese Patent Application Laid-Open Publication No. 2016-12712
disclose techniques for forming a protective film on the inner wall
surface of a chamber. In the technique disclosed in each of these
literatures, plasma of a silicon-containing gas is generated in the
chamber in order to form a protective film on the inner wall
surface of the chamber.
SUMMARY
[0004] In an exemplary embodiment, a plasma processing method is
provided. The plasma processing method is performed using a plasma
processing apparatus. The plasma processing apparatus includes a
chamber, a substrate support, an upper electrode, a radio frequency
power source, and a direct-current power source device. The chamber
includes a side wall having an inner wall surface. The substrate
support includes a lower electrode provided in the chamber. The
upper electrode is provided above the substrate support. The radio
frequency power source is used to generate plasma in the chamber.
The direct-current power source device is electrically connected to
the upper electrode. The direct-current power source device is
configured to periodically generate a pulsed negative
direct-current voltage. The plasma processing method includes
generating plasma from a film formation gas in the chamber by
supplying radio frequency power from the radio frequency power
source. The plasma processing method further includes forming a
protective film on the inner wall surface by depositing the
chemical species from the plasma on the inner wall surface. In the
forming a protective film, the pulsed negative direct-current
voltage is periodically applied from the direct-current power
source device to the upper electrode.
[0005] The foregoing summary is illustrative only and is not
intended to be in any way limiting. In addition to the illustrative
aspects, exemplary embodiments, and features described above,
further aspects, exemplary embodiments, and features will become
apparent by reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a flowchart of a plasma processing method
according to an exemplary embodiment.
[0007] FIG. 2 schematically illustrates a plasma processing
apparatus according to an exemplary embodiment.
[0008] FIG. 3 illustrates an example of a configuration of a
direct-current power source device of the plasma processing
apparatus shown in FIG. 2.
[0009] FIG. 4 is a timing chart related to the plasma processing
method according to an exemplary embodiment.
[0010] FIG. 5 is a graph showing experimental results.
DETAILED DESCRIPTION
[0011] Hereinafter, various exemplary embodiments will be
described.
[0012] In an exemplary embodiment, a plasma processing method is
provided. The plasma processing method is performed using a plasma
processing apparatus. The plasma processing apparatus includes a
chamber, a substrate support, an upper electrode, a radio frequency
power source, and a direct-current power source device. The chamber
includes a side wall having an inner wall surface. The substrate
support includes a lower electrode provided in the chamber. The
upper electrode is provided above the substrate support. The radio
frequency power source is used to generate plasma in the chamber.
The direct-current power source device is electrically connected to
the upper electrode. The direct-current power source device is
configured to periodically generate a pulsed negative
direct-current voltage. The plasma processing method includes
generating plasma from a film formation gas in the chamber by
supplying radio frequency power from the radio frequency power
source. The plasma processing method further includes forming a
protective film on the inner wall surface by depositing the
chemical species from the plasma on the inner wall surface. In the
forming a protective film, the pulsed negative direct-current
voltage is periodically applied from the direct-current power
source device to the upper electrode.
[0013] In the above embodiment, a raw material in the plasma formed
from the film formation gas forms the protective film on the
surface of the upper electrode and the inner wall surface of the
side wall of the chamber. Since the pulsed negative direct-current
voltage is periodically applied to the upper electrode when the
protective film is formed, ion sputtering occurs on the protective
film formed on the surface of the upper electrode. As a result, an
increase in the thickness of the protective film formed on the
surface of the upper electrode is suppressed. On the other hand,
the thickness of the protective film which is formed on the inner
wall surface of the side wall of the chamber is adjusted according
to the effective value of the voltage which is applied from the
direct-current power source device to the upper electrode when the
protective film is formed. Therefore, according to the above
embodiment, it becomes possible to control the thickness of the
protective film which is formed on the inner wall surface of the
side wall of the chamber, while suppressing an increase in the
thickness of the protective film which is formed on the upper
electrode of a capacitively coupled plasma processing
apparatus.
[0014] In an exemplary embodiment, the film formation gas may
include a silicon-containing gas. In an exemplary embodiment, the
silicon-containing gas may be a silicon halide gas. In an exemplary
embodiment, the silicon halide gas may be a silicon tetrachloride
gas. In an exemplary embodiment, the film formation gas may include
a carbon-containing gas. In an exemplary embodiment, the
carbon-containing gas may be a hydrocarbon gas or a fluorocarbon
gas.
[0015] In an exemplary embodiment, an output voltage of the
direct-current power source device may be a pulsed negative
direct-current voltage in a first period within a cycle and be zero
volts in a second period remaining within the cycle.
[0016] In an exemplary embodiment, the effective value of the
output voltage of the direct-current power source device in the
forming a protective film may be smaller than 0 V and equal to or
larger than -848 V. The effective value is the product of the
square root of a duty ratio and the value of the pulsed negative
direct-current voltage in the first period. The duty ratio is the
ratio of the time length of the first period to the time length of
the cycle.
[0017] In an exemplary embodiment, the plasma processing method may
further include performing plasma processing of a substrate in the
chamber after the forming a protective film. In the performing
plasma processing, plasma is generated from a processing gas in the
chamber by supplying radio frequency power from the radio frequency
power source. In the performing plasma processing, the effective
value of the output voltage of the direct-current power source
device is set to a value smaller than the effective value in the
forming a protective film. In the performing plasma processing, the
substrate is processed by a chemical species from the plasma
generated from the processing gas.
[0018] In an exemplary embodiment, the plasma processing method may
further include removing the protective film. In the removing the
protective film, plasma is generated from a cleaning gas in the
chamber by supplying radio frequency power from the radio frequency
power source. In the removing the protective film, the effective
value of the output voltage of the direct-current power source
device is set to a value larger than the effective value in the
forming a protective film. In the removing the protective film, the
protective film is processed by a chemical species from the plasma
generated from the cleaning gas.
[0019] In another exemplary embodiment, a plasma processing
apparatus is provided. The plasma processing apparatus includes a
chamber, a substrate support, an upper electrode, a radio frequency
power source, a direct-current power source device, and a
controller. The chamber includes a side wall having an inner wall
surface. The substrate support includes a lower electrode provided
in the chamber. The upper electrode is provided above the substrate
support. The radio frequency power source is used to generate
plasma in the chamber. The direct-current power source device is
electrically connected to the upper electrode. The controller is
configured to control the radio frequency power source and the
direct-current power source device. The direct-current power source
device is configured to periodically generate a pulsed negative
direct-current voltage. The controller is configured to control the
radio frequency power source to supply radio frequency power to
generate plasma from a film formation gas in the chamber. The
controller is configured to control the direct-current power source
device to periodically apply the pulsed negative direct-current
voltage to the upper electrode to form a protective film on the
inner wall surface by depositing the chemical species from the
plasma on the inner wall surface.
[0020] In an exemplary embodiment, the film formation gas may
include a silicon-containing gas. In an exemplary embodiment, the
silicon-containing gas may be a silicon halide gas. In an exemplary
embodiment, the silicon halide gas may be a silicon tetrachloride
gas. In an exemplary embodiment, the film formation gas may include
a carbon-containing gas. In an exemplary embodiment, the
carbon-containing gas may be a hydrocarbon gas or a fluorocarbon
gas.
[0021] In an exemplary embodiment, an output voltage of the
direct-current power source device may be a pulsed negative
direct-current voltage in a first period within a cycle and be zero
volts in a second period remaining within the cycle.
[0022] In an exemplary embodiment, the controller may be configured
to control the direct-current power source device to set the
effective value of the output voltage to a value smaller than 0 V
and equal to or larger than -848 V when forming a protective film.
The effective value is the product of the square root of a duty
ratio and the value of the pulsed negative direct-current voltage
in the first period. The duty ratio is the ratio of the time length
of the first period to the time length of the cycle.
[0023] In an exemplary embodiment, the controller may be configured
to control the radio frequency power source to supply radio
frequency power to generate plasma from a processing gas in the
chamber when performing plasma processing of the substrate in the
chamber after the formation of the protective film. The controller
may be configured to control the direct-current power source device
to set the effective value of the output voltage of the
direct-current power source device to a value smaller than the
effective value set at the time of the formation of the protective
film, when performing the plasma processing of the substrate.
[0024] In an exemplary embodiment, the controller may be configured
to control the radio frequency power source to supply radio
frequency power to generate plasma from the cleaning gas in the
chamber when removing the protective film. The controller may
control the direct-current power source device to set the effective
value of the output voltage of the direct-current power source
device to a value larger than the effective value set at the time
of the formation of the protective film, when removing the
protective film.
[0025] Hereinafter, various embodiments will be described in detail
with reference to the drawings. In the drawing, the same or
equivalent portions are denoted by the same reference symbols.
[0026] FIG. 1 is a flowchart of a plasma processing method
according to an exemplary embodiment. The plasma processing method
(hereinafter referred to as a "method MT") shown in FIG. 1 is
performed using a capacitively coupled plasma processing apparatus.
FIG. 2 schematically illustrates a plasma processing apparatus
according to an exemplary embodiment. A plasma processing apparatus
1 shown in FIG. 2 is a capacitively coupled plasma processing
apparatus. The plasma processing apparatus 1 may be used in
performing the method MT.
[0027] The plasma processing apparatus 1 is provided with a chamber
10. The chamber 10 provides an internal space 10s therein. The
chamber 10 includes a chamber body 12. The chamber body 12 has a
substantially cylindrical shape. The internal space 10s is provided
inside the chamber body 12. The chamber body 12 is formed of a
conductor such as aluminum. The chamber body 12 is grounded. A film
having corrosion resistance is applied to the inner wall surface of
the chamber body 12. The film having corrosion resistance may be a
film formed of ceramic such as aluminum oxide or yttrium oxide.
[0028] A passage 12p is formed in the side wall of the chamber body
12. A substrate W passes through the passage 12p when it is
transferred between the internal space 10s and the outside of the
chamber 10. The passage 12p is configured to be able to be opened
and closed by a gate valve 12g. The gate valve 12g is provided
along the side wall of the chamber body 12.
[0029] A support 13 is provided on a bottom portion of the chamber
body 12. The support 13 is formed of an insulating material. The
support 13 has a substantially cylindrical shape. The support 13
extends upward from the bottom portion of the chamber body 12 in
the internal space 10s. The support 13 supports a substrate support
14. The substrate support 14 is configured to support the substrate
W in the chamber 10, that is, in the internal space 10s.
[0030] The substrate support 14 includes a lower electrode 18 and
an electrostatic chuck 20. The lower electrode 18 and the
electrostatic chuck 20 are provided in the chamber 10. The
substrate support 14 may further include an electrode plate 16. The
electrode plate 16 is formed of a conductor such as aluminum, for
example, and has a substantially disk shape. The lower electrode 18
is provided on the electrode plate 16. The lower electrode 18 is
formed of a conductor such as aluminum, for example, and has a
substantially disk shape. The lower electrode 18 is electrically
connected to the electrode plate 16.
[0031] The electrostatic chuck 20 is provided on the lower
electrode 18. The substrate W is placed on an upper surface of the
electrostatic chuck 20. The electrostatic chuck 20 has a main body
and an electrode. The main body of the electrostatic chuck 20 is
formed of a dielectric. The electrode of the electrostatic chuck 20
is an electrode having a film shape and is provided in the main
body of the electrostatic chuck 20. The electrode of the
electrostatic chuck 20 is connected to a direct-current power
source 20p through a switch 20s. When the voltage from the
direct-current power source 20p is applied to the electrode of the
electrostatic chuck 20, an electrostatic attraction force is
generated between the electrostatic chuck 20 and the substrate W.
Due to the generated electrostatic attraction force, the substrate
W is attracted to the electrostatic chuck 20 and held by the
electrostatic chuck 20.
[0032] An edge ring ER is disposed on the substrate support 14. The
edge ring ER may be formed of silicon, silicon carbide, or quartz,
but not limited thereto. When processing of the substrate W is
performed in the chamber 10, the substrate W is disposed on the
electrostatic chuck 20 and in a region surrounded by the edge ring
ER.
[0033] A flow path 18f is provided in the interior of the lower
electrode 18. A heat exchange medium (for example, a refrigerant)
is supplied from a chiller unit 22 to the flow path 18f through a
pipe 22a. The chiller unit 22 is provided outside the chamber 10.
The heat exchange medium supplied to the flow path 18f is returned
to the chiller unit 22 through a pipe 22b. In the plasma processing
apparatus 1, the temperature of the substrate W placed on the
electrostatic chuck 20 is adjusted by the heat exchange between the
heat exchange medium and the lower electrode 18.
[0034] The plasma processing apparatus 1 may be further provided
with a gas supply line 24. The gas supply line 24 supplies a heat
transfer gas (for example, He gas) to a gap between the upper
surface of the electrostatic chuck 20 and the back surface of the
substrate W. The heat transfer gas is supplied from a heat transfer
gas supply mechanism to the gas supply line 24.
[0035] The plasma processing apparatus 1 further includes an upper
electrode 30. The upper electrode 30 is provided above the
substrate support 14. The upper electrode 30 is supported on an
upper portion of the chamber body 12 through a member 32. The
member 32 is formed of a material having insulation properties. The
upper electrode 30 and the member 32 close the upper opening of the
chamber body 12.
[0036] The upper electrode 30 may include a ceiling plate 34 and a
support 36. The lower surface of the ceiling plate 34 is a lower
surface on the internal space 10s side and defines the internal
space 10s. The ceiling plate 34 is formed of a silicon-containing
material. The ceiling plate 34 is formed of, for example, silicon
or silicon carbide. A plurality of gas discharge holes 34a are
formed in the ceiling plate 34. The plurality of gas discharge
holes 34a penetrate the ceiling plate 34 in a plate thickness
direction thereof.
[0037] The support 36 detachably supports the ceiling plate 34. The
support 36 is formed of a conductive material such as aluminum. A
gas diffusion chamber 36a is provided in the interior of the
support 36. A plurality of gas holes 36b are formed in the support
36. The plurality of gas holes 36b extend downward from the gas
diffusion chamber 36a. The plurality of gas holes 36b respectively
communicate with the plurality of gas discharge holes 34a. A gas
introduction port 36c is formed in the support 36. The gas
introduction port 36c is connected to the gas diffusion chamber
36a. A gas supply pipe 38 is connected to the gas introduction port
36c.
[0038] A gas source group 40 is connected to the gas supply pipe 38
through a valve group 41, a flow rate controller group 42, and a
valve group 43. The gas source group 40, the valve group 41, the
flow rate controller group 42, and the valve group 43 configure a
gas supply unit GS. The gas source group 40 includes a plurality of
gas sources. Each of the valve group 41 and the valve group 43
includes a plurality of on-off valves. The flow rate controller
group 42 includes a plurality of flow rate controllers. Each of the
plurality of flow rate controllers of the flow rate controller
group 42 is a mass flow controller or a pressure control type flow
rate controller. Each of the plurality of gas sources of the gas
source group 40 is connected to the gas supply pipe 38 through a
corresponding on-off valve of the valve group 41, a corresponding
flow rate controller of the flow rate controller group 42, and a
corresponding on-off valve of the valve group 43.
[0039] In the plasma processing apparatus 1, a shield 46 is
detachably provided along the inner wall surface of the chamber
body 12. The shield 46 is also provided on the outer periphery of
the support 13. The shield 46 prevents a byproduct of plasma
processing from adhering to the chamber body 12. The shield 46 is
grounded. The shield 46 is configured, for example, by forming a
film having corrosion resistance on a surface of a member formed of
aluminum. The film having corrosion resistance may be a film formed
of ceramic such as yttrium oxide. In an embodiment, the shield 46
provides an inner wall surface 10w which the chamber 10 has. The
inner wall surface 10w includes a first region 10a and a second
region 10b. The first region 10a extends on the side of the
internal space 10s. The second region 10b extends above the
internal space 10s and on the side of the upper electrode 30. The
first region 10a and the second region 10b may be provided by
another member, for example the chamber body 12, instead of the
shield 46.
[0040] A baffle plate 48 is provided between the support 13 and the
side wall of the chamber body 12. The baffle plate 48 is
configured, for example, by forming a film having corrosion
resistance on a surface of a member formed of aluminum. The film
having corrosion resistance may be a film formed of ceramic such as
yttrium oxide. A plurality of through-holes are formed in the
baffle plate 48. An exhaust port 12e is provided below the baffle
plate 48 and in the bottom portion of the chamber body 12. An
exhaust device 50 is connected to the exhaust port 12e through an
exhaust pipe 52. The exhaust device 50 has a pressure adjusting
valve and a vacuum pump such as a turbo molecular pump.
[0041] The plasma processing apparatus 1 further includes a first
radio frequency power source 62 and a second radio frequency power
source 64. The first radio frequency power source 62 is a power
source configured to generate first radio frequency power. In an
example, the first radio frequency power has a frequency suitable
for the generation of a plasma. The frequency of the first radio
frequency power is, for example, a frequency in a range of 27 MHz
to 100 MHz. The first radio frequency power source 62 is connected
to the upper electrode 30 through a matcher 66. The matcher 66 has
a circuit configured to match the impedance on the load side (the
upper electrode 30 side) of the first radio frequency power source
62 with the output impedance of the first radio frequency power
source 62. The first radio frequency power source 62 may be
connected to the lower electrode 18 through the matcher 66 and the
electrode plate 16.
[0042] The second radio frequency power source 64 is a power source
configured to generate second radio frequency power. The second
radio frequency power has a frequency lower than the frequency of
the first radio frequency power. The second radio frequency power
may be used as bias radio frequency power for attracting ions to
the substrate W. The frequency of the second radio frequency power
is, for example, a frequency in a range of 400 kHz to 40 MHz. The
second radio frequency power source 64 is connected to the lower
electrode 18 through a matcher 68 and the electrode plate 16. The
matcher 68 has a circuit configured to match the impedance on the
load side (the lower electrode 18 side) of the second radio
frequency power source 64 with the output impedance of the second
radio frequency power source 64.
[0043] The plasma processing apparatus 1 further includes a
direct-current power source device 70. The direct-current power
source device 70 is electrically connected to the upper electrode
30. The direct-current power source device 70 is configured to
periodically generate a pulsed negative direct-current voltage.
FIG. 3 illustrates an example of a configuration of the
direct-current power source device of the plasma processing
apparatus shown in FIG. 2. FIG. 4 is a timing chart of a plasma
processing method which is performed by using the plasma processing
apparatus according to an exemplary embodiment. In FIG. 4, the
horizontal axis represents time. In FIG. 4, the vertical axis
represents supply of radio frequency power (the first radio
frequency power and/or the second radio frequency power), and the
output voltage of the direct-current power source device 70. In
FIG. 4, a high level of radio frequency power indicates that the
radio frequency power is being supplied. In FIG. 4, a low level of
radio frequency power indicates that the radio frequency power is
not supplied. Hereinafter, FIGS. 3 and 4 will be referred to
together with FIG. 2.
[0044] In an embodiment, the direct-current power source device 70
includes a variable direct-current power source 70a and a switching
device 70b. The variable direct-current power source 70a is
configured to generate a negative direct-current voltage
continuously. The level of the negative direct-current voltage
which is output from the variable direct-current power source 70a
may be controlled by a controller 80, which will be described
later. The switching device 70b switches connection and
disconnection between the variable direct-current power source 70a
and the upper electrode 30 by switching of a conduction state
thereof. The switching of the conduction state of the switching
device 70b may be controlled by the controller 80.
[0045] In order to output the pulsed negative direct-current
voltage, the output voltage of the direct-current power source
device 70 is a negative direct-current voltage in a first period P1
in a cycle PT. In an embodiment, the conduction state of the
switching device 70b is switched such that the variable
direct-current power source 70a and the upper electrode 30 are
connected to each other, in the first period P1 within the cycle
PT. The output voltage of the direct-current power source device 70
is zero volts in the second period P2 remaining in the cycle PT. In
an embodiment, the conduction state of the switching device 70b is
switched such that connection between the variable direct-current
power source 70a and the upper electrode 30 is disconnected, in the
second period P2 within the cycle PT.
[0046] In an embodiment, a frequency f that is the reciprocal of
the cycle PT may be 400 kHz or more. In an embodiment, the
frequency f may be 1 MHz or less. In a case where the frequency f
is 1 MHz or less, the independent controllability of the behavior
of ions with respect to the generation of radicals in the chamber
10 is enhanced.
[0047] The plasma processing apparatus 1 further includes the
controller 80. The controller 80 may be a computer which includes a
processor, a storage unit such as a memory, an input device, a
display device, a signal input/output interface, and the like. The
controller 80 controls each part of the plasma processing apparatus
1. In the controller 80, an operator can perform a command input
operation and the like by using the input device in order to manage
the plasma processing apparatus 1. Further, in the controller 80,
the visualized operating status of the plasma processing apparatus
1 can be displayed by the display device. Further, a control
program and recipe data are stored in the storage unit of the
controller 80. The control program is executed by the processor of
the controller 80 to perform various processing in the plasma
processing apparatus 1. The processor of the controller 80 executes
the control program and controls each part of the plasma processing
apparatus 1 according to the recipe data, whereby the method MT is
performed in the plasma processing apparatus 1.
[0048] Hereinafter, the method MT will be described with reference
to FIG. 1 again, taking as an example a case where the method is
performed using the plasma processing apparatus 1. Further, the
control of each part of the plasma processing apparatus 1 by the
controller 80 will also be described.
[0049] The method MT includes step ST1 and step ST2. During
performing step ST1 and step ST2, a substrate (for example, a dummy
substrate) may or may not be placed on the substrate support
14.
[0050] In step ST1, plasma is generated from a film formation gas
in the chamber 10. In step ST1, the film formation gas is supplied
from the gas supply unit GS into the chamber 10 in order to
generate plasma from a film formation gas in the chamber 10. The
film formation gas is a gas containing a raw material of a
protective film to be formed on the inner wall surface 10w. The
film formation gas may include a silicon-containing gas as a raw
material gas. In this case, a silicon-containing film is formed as
the protective film. The silicon-containing gas may be a silicon
halide gas. The silicon halide gas may be a silicon tetrachloride
gas. In step ST1, one or more other gases may be supplied into the
chamber 10, in addition to the raw material gas. That is, in step
ST1, a mixed gas containing the raw material gas may be supplied
into the chamber 10. One or more other gases may be an oxygen gas
and a noble gas (for example, an argon gas). In a case where the
film formation gas contains an oxygen gas, a silicon oxide film is
formed as the protective film. The film formation gas may include
another raw material gas instead of the silicon-containing gas. For
example, the film formation gas may include a carbon-containing gas
as the raw material gas. In this case, a carbon-containing film is
formed as the protective film. The carbon-containing gas may be a
hydrocarbon gas such as a CH.sub.4 gas, or a fluorocarbon gas such
as a C.sub.4F.sub.6 gas. Further, in step ST1, the first radio
frequency power and/or the second radio frequency power is supplied
in order to form plasma from the film formation gas in the chamber
10. As a result, plasma is generated from the film formation gas in
the chamber 10. In step ST1, the second radio frequency power may
not be supplied.
[0051] For the execution of step ST1, the controller 80 controls
the gas supply unit GS to supply the film formation gas into the
chamber 10. For the execution of step ST1, the controller 80
controls the exhaust device 50 to set the pressure in the chamber
10 to a specified pressure. For the execution of the process ST1,
the controller 80 controls the first radio frequency power source
62 and/or the second radio frequency power source 64 to supply the
first radio frequency power and/or the second radio frequency
power.
[0052] Step ST2 is performed during the generation of plasma in
step ST1. In step ST2, a protective film is formed on the inner
wall surface 10w by depositing the chemical species from the plasma
generated from the film formation gas in step ST1 on the inner wall
surface 10w. In step ST2, a pulsed negative direct-current voltage
is periodically applied from the direct-current power source device
70 to the upper electrode 30. As described above, the output
voltage of the direct-current power source device 70 is a pulsed
negative direct-current voltage in the first period P1 within the
cycle PT. The output voltage of the direct-current power source
device 70 is zero volts in the second period P2 remaining within
the cycle PT.
[0053] In an embodiment, the effective value of the output voltage
of the direct-current power source device 70 in step ST2 is smaller
than 0 V and equal to or larger than -848 V. The effective value is
the product of the square root of a duty ratio (expressed as a
decimal number) of the pulsed negative direct-current voltage and
the value of the pulsed negative direct-current voltage in the
first period P1. The duty ratio is the ratio (expressed as a
decimal number) of the time length of the first period P1 to the
time length of the cycle PT. In an embodiment, the duty ratio of
the pulsed negative direct-current voltage may be 0.2 or more and
0.5 or less. In an embodiment, the value of the pulsed negative
direct-current voltage in the first period P1 may be smaller than 0
V and equal to or larger than --1200 V.
[0054] For the execution of step ST2, the controller 80 controls
the direct-current power source device to periodically apply a
pulsed negative direct-current voltage to the upper electrode 30.
In an embodiment, the controller 80 controls the direct-current
power source device 70 to set the effective value of the output
voltage of the direct-current power source device 70 to a value
smaller than 0 V and equal to or larger than -848 V.
[0055] In the method MT, the raw material in the plasma formed from
the film formation gas forms a protective film on the surface of
the upper electrode 30 and the inner wall surface 10w of the side
wall of the chamber 10. At the time of the formation of the
protective film, the pulsed negative direct-current voltage is
periodically applied to the upper electrode 30, and therefore, ion
sputtering occurs on the protective film formed on the surface of
the upper electrode 30. As a result, an increase in the thickness
of the protective film formed on the surface of the upper electrode
30 is suppressed. On the other hand, the thickness of the
protective film which is formed on the inner wall surface 10w is
adjusted according to the effective value of the voltage which is
applied from the direct-current power source device 70 to the upper
electrode 30 when the protective film is formed. Therefore,
according to the method MT, it becomes possible to control the
thickness of the protective film which is formed on the inner wall
surface 10w, while suppressing an increase in the thickness of the
protective film which is formed on the upper electrode 30 of the
capacitively coupled plasma processing apparatus 1.
[0056] In an embodiment, the method MT may further include step
ST3. Step ST3 is performed after step ST2. In step ST3, plasma
processing of the substrate is performed in the chamber 10. During
performing step ST3, the substrate is placed on the substrate
support 14 and held by the electrostatic chuck 20. The plasma
processing which is performed in step ST3 may be plasma etching.
The plasma processing which is performed in step ST3 may be another
plasma processing.
[0057] In step ST3, a processing gas is supplied from the gas
supply unit GS into the chamber 10. The processing gas is
appropriately selected according to the plasma processing which is
applied to the substrate. In step ST3, the first radio frequency
power and/or the second radio frequency power is supplied in order
to generate plasma from the processing gas in the chamber 10. As a
result, plasma is generated from the processing gas in the chamber
10. In step ST3, the substrate is processed by the chemical species
from the plasma generated from the processing gas. In step ST3, the
effective value of the output voltage of the direct-current power
source device 70 is set to a value smaller than the effective value
in step ST2. As a result, the reduction of the protective film
during the execution of step ST3 is suppressed.
[0058] For the execution of step ST3, the controller 80 controls
the gas supply unit GS to supply the processing gas into the
chamber 10. For the execution of step ST3, the controller 80
controls the exhaust device 50 to set the pressure in the chamber
10 to a specified pressure. For the execution of step ST3, the
controller 80 controls the first radio frequency power source 62
and/or the second radio frequency power source 64 to supply the
first radio frequency power and/or the second radio frequency
power. Further, for the execution of step ST3, the controller 80
controls the direct-current power source device 70 to set the
effective value of the output voltage of the direct-current power
source device 70 to a value smaller than the effective value set in
step ST2.
[0059] In an embodiment, the method MT may further include step
ST4. In step ST4, the protective film formed in step ST2 is
removed. During the execution of step ST4, a substrate (for
example, a dummy substrate) may or may not be placed on the
substrate support 14.
[0060] In step ST4, a cleaning gas is supplied from the gas supply
unit GS into the chamber 10. In a case where the protective film is
a silicon oxide film, the cleaning gas may include a fluorocarbon
gas (for example, a CF.sub.4 gas). In a case where the protective
film is a carbon-containing film, the cleaning gas may include an
oxygen-containing gas (for example, an O.sub.2 gas). In step ST4,
the first radio frequency power and/or the second radio frequency
power is supplied to generate plasma from the cleaning gas in the
chamber 10. As a result, plasma is generated from the cleaning gas
in the chamber 10. In step ST4, the protective film is removed by
the chemical species from the plasma generated from the cleaning
gas. In step ST4, the effective value of the output voltage of the
direct-current power source device 70 is set to a value larger than
the effective value in step ST2. As a result, the efficiency of
removing the protective film in step ST4 is improved.
[0061] For the execution of step ST4, the controller 80 controls
the gas supply unit GS to supply the cleaning gas into the chamber
10. For the execution of step ST4, the controller 80 controls the
exhaust device 50 to set the pressure in the chamber 10 to a
specified pressure. For the execution of step ST4, the controller
80 controls the first radio frequency power source 62 and/or the
second radio frequency power source 64 to supply the first radio
frequency power and/or the second radio frequency power. Further,
for the execution of step ST4, the controller 80 controls the
direct-current power source device 70 to set the effective value of
the output voltage of the direct-current power source device 70 to
a value larger than the effective value set in step ST2.
[0062] In an embodiment, the method MT may further include step
ST5. In step ST5, it is determined whether or not a stop condition
is satisfied. It is determined that the stop condition is be
satisfied, for example, in a case where the number of executions of
the sequence including step ST1 to step ST4 has reached a
predetermined number of times. In a case where it is determined in
step ST5 that the stop condition is not satisfied, the sequence
including step ST1 to step ST4 is further executed. In step ST3 in
the sequence which is further executed, plasma processing is
further executed on the substrate processed in step ST3 in the
previous sequence, or plasma processing is executed on another
substrate. In a case where it is determined in step ST5 that the
stop condition is satisfied is made, the method MT is ended.
[0063] While various exemplary embodiments have been described
above, various additions, omissions, substitutions and changes may
be made without being limited to the exemplary embodiments
described above. Elements of the different embodiments may be
combined to form another embodiment.
[0064] Hereinafter, an experiment performed in order to evaluate
the method MT and the plasma processing apparatus 1 will be
described. It should be noted that the present disclosure is not
limited by the experiment described below.
[0065] In the experiment, step ST1 and step ST2 were performed in a
state where a first chip was attached to the surface on the
internal space 10s side of the upper electrode 30, a second chip
was attached to the first region 10a, and a third chip was attached
to the second region 10b. In the experiment, the effective value of
the output voltage of the direct-current power source device 70 in
step ST2 was set to various values. The conditions of step ST1 in
the experiment are shown below.
Conditions of step ST1
[0066] Pressure in chamber 10: 20 mTorr (2.666 Pa)
[0067] Flow rate of silicon tetrachloride gas: 5 sccm
[0068] Flow rate of oxygen gas: 50 sccm
[0069] Flow rate of argon gas: 250 sccm
[0070] First radio frequency power: 60 MHz, 1000 W
[0071] Second radio frequency power: 0 W
[0072] Frequency f (reciprocal of cycle PT): 400 kHz
[0073] Duty ratio of pulsed negative direct-current voltage: 0.3 or
0.5
[0074] Value of pulsed negative direct-current voltage: 0 V, -500
V, or -900 V
[0075] In the experiment, the thickness of the protective film
formed on each chip under each setting of the effective value of
the output voltage of the direct-current power source device 70 was
measured. Then, the ratio of the film thickness of the protective
film formed on each chip to a reference film thickness, that is, a
film thickness ratio (percentage), was obtained. Here, the
reference film thickness is the film thickness of the protective
film formed on a chip attached to the same location when the
effective value of the output voltage of the direct-current power
source device 70 in step ST2 is 0 V.
[0076] FIG. 5 shows a graph showing the results of the experiment.
In the graph of FIG. 5, the horizontal axis represents the
effective value of the output voltage of the direct-current power
source device 70 in step ST2. In the graph of FIG. 5, the vertical
axis represents the obtained film thickness ratio. In FIG. 5, first
to third film thickness ratios indicate the film thickness ratios
of the protective films formed on the first to third chips,
respectively. As shown in FIG. 5, the first film thickness ratio
decreases as the absolute value of the effective value of the
output voltage of the direct-current power source device 70
increases. From this, it is confirmed that an increase in the film
thickness of the protective film which is formed on the surface of
the upper electrode 30 can be suppressed by periodically applying a
pulsed negative direct-current voltage from the direct-current
power source device 70 to the upper electrode 30 during the
generation of the plasma of the film formation gas. Further, it is
confirmed that the film thickness of the protective film which is
formed on the surface of the upper electrode 30 decreases as the
absolute value of the effective value of the output voltage of the
direct-current power source device 70 increases.
[0077] On the other hand, as shown in FIG. 5, the second film
thickness ratio and the third film thickness ratio increase as the
absolute value of the effective value of the output voltage of the
direct-current power source device 70 increases. From this, it is
confirmed that the film thickness of the protective film which is
formed on the inner wall surface 10w of the side wall of the
chamber 10 can be adjusted according to the effective value of the
voltage which is applied from the direct-current power source
device 70 to the upper electrode when the protective film is
formed.
[0078] From the foregoing description, it will be appreciated that
various embodiments of the present disclosure have been described
herein for purposes of illustration, and that various modifications
may be made without departing from the scope and spirit of the
present disclosure. Accordingly, the various embodiments disclosed
herein are not intended to be limiting, with the true scope and
spirit being indicated by the following claims.
* * * * *